我试图将ImageList添加到我的应用程序.我成功添加了它.它显示了我被选中的银行徽标.我通过HashMap进行了添加,因为我想在单击日志图像时使用银行名称.
但是我无法在onItemClick方法中获得银行名称.谁能帮我解决这个问题?
这是我的活动代码.
public void getImageData() {
map = new HashMap<String, String>();
try {
JSONObject jsonResponse = new JSONObject(strJson1);
JSONArray jsonMainNode = jsonResponse.optJSONArray("bank");
for (int i = 0; i < jsonMainNode.length(); i++) {
JSONObject jsonChildNode = jsonMainNode.getJSONObject(i);
img_url = jsonChildNode.optString("logo");
String test1 = img_test_url + img_url;
bName = jsonChildNode.optString("name");
map.put(bName, test1);
}
ItemsAdapter adapter = new ItemsAdapter(getApplicationContext(),map);
list.setAdapter(adapter);
} catch (JSONException e) {
Toast.makeText(getApplicationContext(), "Connection Error...",
Toast.LENGTH_LONG).show();
}
list.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,
long arg3) {
// TODO Auto-generated method stub
HashMap<String, String> obj = (HashMap<String, String>) adapter.getItem(arg2);
String name = (String) obj.get("bName");
Log.d("Bank Name", name);
}
});
}
这是我的适配器类
public class ItemsAdapter extends BaseAdapter {
private final Context context;
ImageView imageView;
private String[] mKeys;
HashMap<String, String> map;
ItemsAdapter(Context context, HashMap<String, String> map) {
this.context = context;
this.map = map;
mKeys = map.keySet().toArray(new String[map.size()]);
}
@Override
public int getCount() {
// TODO Auto-generated method stub
return map.size();
}
@Override
public Object getItem(int position) {
return map.get(mKeys[position]);
}
@Override
public long getItemId(int position) {
// TODO Auto-generated method stub
return position;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
String key = mKeys[position];
String Value = getItem(position).toString();
LayoutInflater inflater = (LayoutInflater) context
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View rowView = convertView;
if (null == convertView)
rowView = inflater.inflate(R.layout.items, parent, false);
imageView = (ImageView) rowView.findViewById(R.id.imageView1);
Bitmap bitmap;
URL imageURL = null;
Log.d("value", Value);
Log.d("key", key);
try {
imageURL = new URL(Value);
}
catch (MalformedURLException e) {
e.printStackTrace();
}
try {
HttpURLConnection connection = (HttpURLConnection) imageURL.openConnection();
connection.setDoInput(true);
connection.connect();
InputStream inputStream = connection.getInputStream();
bitmap = BitmapFactory.decodeStream(inputStream);// Convert to bitmap
imageView.setImageBitmap(bitmap);
} catch (IOException e) {
e.printStackTrace();
}
return rowView ;
}
}
这是LogCat错误.
03-17 13:58:13.620: E/AndroidRuntime(10172): FATAL EXCEPTION: main
03-17 13:58:13.620: E/AndroidRuntime(10172): java.lang.NullPointerException
03-17 13:58:13.620: E/AndroidRuntime(10172): at com.example.testhashimage.MainActivity$1.onItemClick(MainActivity.java:161)
03-17 13:58:13.620: E/AndroidRuntime(10172): at android.widget.AdapterView.performItemClick(AdapterView.java:301)
03-17 13:58:13.620: E/AndroidRuntime(10172): at android.widget.AbsListView.performItemClick(AbsListView.java:1280)
03-17 13:58:13.620: E/AndroidRuntime(10172): at android.widget.AbsListView$PerformClick.run(AbsListView.java:3071)
03-17 13:58:13.620: E/AndroidRuntime(10172): at android.widget.AbsListView$1.run(AbsListView.java:3973)
03-17 13:58:13.620: E/AndroidRuntime(10172): at android.os.Handler.handleCallback(Handler.java:615)
03-17 13:58:13.620: E/AndroidRuntime(10172): at android.os.Handler.dispatchMessage(Handler.java:92)
03-17 13:58:13.620: E/AndroidRuntime(10172): at android.os.Looper.loop(Looper.java:137)
03-17 13:58:13.620: E/AndroidRuntime(10172): at android.app.ActivityThread.main(ActivityThread.java:4960)
03-17 13:58:13.620: E/AndroidRuntime(10172): at java.lang.reflect.Method.invokeNative(Native Method)
03-17 13:58:13.620: E/AndroidRuntime(10172): at java.lang.reflect.Method.invoke(Method.java:511)
03-17 13:58:13.620: E/AndroidRuntime(10172): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1038)
03-17 13:58:13.620: E/AndroidRuntime(10172): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:805)
03-17 13:58:13.620: E/AndroidRuntime(10172): at dalvik.system.NativeStart.main(Native Method)
解决方法:
您有两个错误.首先,您正在尝试访问未初始化的成员类,因为您要对成员类的作用域进行hd重定义具有本地作用域的变量.这很容易修复.您可以使用
@Override
public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,
long arg3) {
onItemClick的firs参数来检索位置的元素.您的情况是:
arg0.getItemAtPosition(arg2)
第二个错误是您正在将字符串转换为HashMap.您的getItem返回:
map.get(mKeys[position]);
并且由于您声明了HashMap< String,String>在您的自定义适配器中,getItem实际上是返回一个String实例.所以你选错了演员.修复NPE后,您将立即收到ClassCastException
编辑:实现您想要的,您应该从
>将表单HashMap切换到另一种,基于索引的,基于订单的集合.例如,它可以是ArrayList< Pair< String,String>> ;,也可以创建自己的javabean.我假设您将使用Pair类,其中id为第一个元素,而url为第二个值
>相应地更改getView和getItem.你可以摆脱
String key = mKeys[position];
String Value = getItem(position).toString();
您的getItem将如下所示:
@Override
public Object getItem(int position) {
return dataset.get(position);
}
并且getView将以
@Override
public View getView(int position, View convertView, ViewGroup parent) {
Pair<String, String> item = (Pair<String, String>)getItem(position);
String Value = item.second;
}
在onItemClick内,您将得到类似的内容:
list.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,
long arg3) {
Pair<String, String> item = (Pair<String, String>)arg0.getItemAtPosition(arg2);
String id = item.first;
}
正如@Raghunandan正确指出的那样,您应该将所有与网络/阻止相关的操作都放到另一个线程中.对Android友好的最简单的方法是使用AsyncTask.您可以阅读this指南.
标签:android-listview,android 来源: https://codeday.me/bug/20191122/2056002.html
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